2-ethylhexyl (4-chloro-2-methylphenoxy)acetate

Toxicity to microorganisms

Administrative data

Endpoint:

toxicity to microorganisms, other

Remarks:

GROWTH INHIBITION TEST according to OECD Guideline No 201/ method C.3.

Type of information:

experimental study

Adequacy of study:

key study

Study period:

02.12.2008 - 12.12.2008

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2008

Report date:

2008

Materials and methods

Test guideline

Guideline:

other: Study performed according to OECD Guideline No 201/ method C.3.

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

2-ethylhexyl (4-chloro-2-methylphenoxy)acetate

EC Number:

249-636-2

EC Name:

2-ethylhexyl (4-chloro-2-methylphenoxy)acetate

Cas Number:

29450-45-1

Molecular formula:

C17H25ClO3

IUPAC Name:

2-ethylhexyl (4-chloro-2-methylphenoxy)acetate

impurity 1

Reference substance name:

(4-chloro-2-methylphenoxy)acetic acid

EC Number:

202-360-6

EC Name:

(4-chloro-2-methylphenoxy)acetic acid

Cas Number:

94-74-6

Molecular formula:

C9H9ClO3

IUPAC Name:

(4-chloro-2-methylphenoxy)acetic acid

Test material form:

liquid

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

72 h

Dose descriptor:

other: EyC50

Remarks:

Mean concentration causing 50% yield inhibition of Anabaena flos-aquae culture

Effect conc.:

16.67 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Effect concentrations 2

Key result

Duration:

72 h

Dose descriptor:

other: ErC50

Remarks:

mean concentration causing 50% inhibition of average specific growth rate

Effect conc.:

32 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Effect concentrations 3

Key result

Duration:

72 h

Dose descriptor:

NOEC

Remarks:

NOEC value for average specific growth rate

Effect conc.:

0.32 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Any other information on results incl. tables

The following results were obtained in the study:

·          increase of biomass in control during 72 h was 22.4 times (criterion – not less than 16 times)

·        coefficient of variation for specific growth rate for control in the whole period of test (t0-t72) is: 3.8% (criterion – not more than 10 %),

·        the mean coefficient of variation for ‘section-by-section’ specific growth rates in the control cultures was 41.3 % (criterion – not more than 35 %)

Breaching of this validity criteria having first two criteria fulfilled has no significant influence on the final study results.

Applicant's summary and conclusion

Executive summary:

Growth inhibition assessment was performed according to the OECD Guideline No 201[1], method C.3, as well as in compliance with Principles of Good Laboratory Practice (GLP, OECD 1997).

The aim of the study was determination of growth inhibition of cyanobacteria Anabaena flos-aquae exposed to the range of concentrations (expressed as the ErCx in mg/L after 24, 48 and 72 h exposure) and also determination of yield inhibition (expressed as the EyCx in mg/L after 24, 48 and 72 h exposure) as well as the values LOEC and NOEC.

Test material was used in 5 concentrations in range from 0.32 mg/L to 32.0 mg/L.

Mean concentration causing 50% yield inhibition of Anabaena flos-aquae culture (EyC50/72 h) is 16.67 mg/L, and mean concentration causing 50% inhibition of average specific growth rate of (ErC50/72 h) is above 32.00 mg/L based on nominal concentration of the test item.

The LOEC and NOEC values are below 0.32 mg/L for yield. The LOEC value for average specific growth rate is 1.0 mg/L, and the NOEC value for average specific growth rate is 0.32 mg/L after 72 h (based on nominal concentrations of the test item).